Long Term Evolution (LTE) is an advanced 3rd Generation mobile communication technology aiming to support a high data rate up to 300 Mbps and packet-switched traffic with seamless mobility. However, the LTE system operates in the bandwidth relatively narrow as compared to a Wireless Local Area Network (WLAN). In contrast, the WLAN system based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard provides high bandwidth and data rate but is lack of mobility support.
In order to exploit the advantages of the LTE and WLAN systems having different characteristics, it is indispensable to secure the seamless mobility between the two systems. The seamless mobility means keeping an uninterrupted connection at all times when moving between two networks and thus requires guaranteeing stable handover. Particularly in the handover between heterogeneous networks, a mobile terminal must perform authentication process with the handover target network, and the connection with the current network is broken after the completion of authentication process.
In case that the mobile terminal is moving fast, however, it is very limited to maintain the connection to the current network. Accordingly, the authentication delay is one of the main factors influencing the stability of the handover.
RFC 5191 defines Protocol for Carrying Authentication for Network Access (PANA) for Extensible Authentication Protocol (EAP) to enable network access authentication between users and access network. In PANA, pre-authentication is used for the handover, however, the LTE adopts an Evolved Packet System-Authentication and Key Agreement (EPS AKA) method rather than EAP authentication method, it is difficult to use the EAP-based authentication in the handover from the WLAN system to the LTE system. Although the pre-authentication method is introduced in IEEE 802.11i, it is a Layer 2 protocol and limited to the WLAN system, thereby being unadoptable for the handover between heterogeneous networks.
There is therefore a need to develop a method for supporting a pre-authentication procedure applicable to the handover between LTE and WLAN systems.